# Publications

## Selected Journal Publications and Book Chapters

- Mieloszyk RJ, Verghese GC, Deitch K, Cooney B, Khalid A, Mirre-González MA, Heldt T, Krauss BS. Automated quantitative analysis of capnogram shape for COPD–Normal and COPD–CHF classification.
*IEEE Transactions on Biomedical Engineering*PP(99): 1, 2014. - Preciado VM, Jadbabaie A, Verghese GC. Structural analysis of Laplacian spectral properties of large-scale networks.
*IEEE Transactions on Automatic Control*58(9): 2338-2343, 2013. - Reisner AT, Heldt T. A computational model of hemorrhage and dehydration suggests a pathophysiological mechanism: Starling-mediated protein trapping.
*American Journal of Physiology*, 304(4):H620-31, 2013. - Heldt T, Verghese GC, Mark RG. Mathematical modeling of physiological systems. In “Mathematical modeling and validation in physiology: applications to the cardiovascular and respiratory systems,” JJ Batzel, M Bachar, F Kappel (eds), Springer Verlag, 2013.
- Kashif FM, Verghese GC, Novak V, Czosnyka M, Heldt T. Model-based noninvasive estimation of intracranial pressure from cerebral blood flow velocity and arterial blood pressure.
*Science Translational Medicine*4 129ra44, 2012. (full-text, reprint) - Heldt T, Kashif FM, Sulemanji M, O’Leary HM, du Plessis AJ, Verghese GC. Continuous quantitative monitoring of cerebral oxygen metabolism in neonates by ventilator-gated analysis of NIRS recordings.
*Acta Neurochirurgica Supplementum*114: 177-180, 2012. - Azunre P, Gomez-Uribe C, Verghese GC. Mass fluctuation kinetics: Analysis and computation of equilibria and local dynamics.
*IET Systems Biology*5(6): 325-335, 2011. - Nemati S, Edwards BA, Sands SA, Berger PJ, Wellman A, Verghese GC, Malhotra A, Butler JP. Model-based characterization of ventilatory stability using spontaneous breathing.
*Journal of Applied Physiology*111(1): 55-67, 2011. - Saeed M, Villaroel M, Reisner AT, Clifford G, Lehman LW, Moody G, Heldt T, Kyaw TG, Moody B, Mark RG. Multiparameter Intelligent Monitoring in Intensive Care II (MIMIC-II): A public-access intensive care unit database.
*Critical Care Medicine*39(5): 952-960, 2011. - Richoux WJ, Verghese GC. A generalized influence model for networked stochastic automata.
*IEEE Trans. Systems, Man and Cybernetics*, Part A (Systems and Humans) 41(1): 10-23, 2011. - Heldt T, Mukkamala R, Moody GB, Mark RG. CVSim: a cardiovascular simulator for teaching and research.
*The Open Pacing, Electrophysiology and Therapy Journal*3: 45-54, 2010. - Preciado VM, Verghese GC. Low-order spectral analysis of the Kirchhoff matrix of a probabilistic graph with prescribed expected degree sequence.
*IEEE Trans. Circuits and Systems*56(6): 1231-1240, 2009. - Zager L, Verghese GC. Epidemic thresholds for infections in uncertain networks.
*Complexity*14(4): 12-25, 2009. - Gomez-Uribe C, Verghese GC, Tzafriri AR. Enhanced identification and exploitation of time scales for model reduction in stochastic chemical kinetics.
*J. Chemical Physics*129 (24): 244112, 2008. - Gomez-Uribe C, Verghese GC, Mirny L.A. Operating regimes of signaling cycles: Statics, dynamics, and noise filtering.
*PLoS Computational Biology*3(12): e246, 2007. - Gomez-Uribe C, Verghese GC. Mass fluctuation kinetics: Capturing stochastic behavior in systems of chemical reactions through coupled mean-variance computations.
*J. Chemical Physics*126(2): 024109, 2007. - Parlikar TA, Heldt T, Verghese GC. Cycle-averaged models of cardiovascular dynamics.
*IEEE Trans. Circuits and Systems I*: Fundamental Theory and Applications 53 (11): 2459 – 2468, 2006. (Special Issue on Advances in Life Sciences Systems and Applications) - Roy S, Verghese GC, Lesieutre BC. Moment-linear stochastic systems. In: Informatics in Control, Automation and Robotics I. J. Braz, H. Araujo, A Vieira, B. Encarnacao (eds.), pp. 263-271, Springer Verlag.
- Heldt T, Chang JL, Chen JJS, Verghese GC, Mark RG. Cycle-averaged dynamics of a periodically-driven, closed-loop circulation model.
*Control Engineering Practice*13(9): 1163 – 1171, 2005. (PMID: 16050064) (Special Issue on Modelling and Control in Biomedical and Biological Systems) - Hadjicostis CN, Verghese GC. Coding approaches to fault tolerance in linear dynamic systems.
*IEEE Trans. Information Theory*51(1): 210-228, 2005. - Eldar YC, Megretski A, Verghese GC. Optimal detection of symmetric mixed quantum states.
*IEEE Trans. Information Theory*50(6): 1198-1207, 2004. - Eldar YC, Megretski A, Verghese GC. Designing optimal quantum detectors via semidefinite programming.
*IEEE Trans. Information Theory*49(4): 1007-1012, 2003. - Hadjicostis CN, Verghese GC. Fault-tolerant computation in semigroups and semirings: Applications to automata, dynamic systems and Petri nets.
*J. Franklin Institute*339: 387-440, 2002. - Hadjicostis CN, Verghese GC. Encoded dynamics for fault tolerance in linear finite-state machines.
*IEEE Trans. Automatic Control*47(1): 2133-2140, 2002. - Asavathiratham C, Roy S, Lesieutre BC, Verghese GC. The influence model.
*IEEE Control Systems Magazine*21(6): 52-64, 2001. (Special Issue on Complex Systems) - Lesieutre BC, Mamishev AV, Keskiner E, Zahn M, Verghese GC. Forward and inverse parameter estimation algorithms of interdigital dielectrometry sensors.
*IEEE Trans. Dielectrics and Electric Insulation*8: 577-588, 2001. - Fiore P, Verghese GC. Constrained maximum likelihood solution of linear equations.
*IEEE Trans. Signal Processing*48: 671-679, 2000. - Hadjicostis CN, Verghese GC. Structured redundancy for fault tolerance in LTI state-space models and Petri nets.
*Kybernetika*35: 39-55, 1999. - Burth M, Vélez-Reyes M, Verghese GC. Improving parameter estimation by subset selection: Application to a model for generator dynamics.
*IEEE Trans. Power Systems*14: 218-225, 1999. - Caliskan VA, Verghese GC, Stankovic AM. Multi-frequency averaging of DC-DC converters.
*IEEE Trans. Power Electronics*14: 124-133, 1999. - Mattavelli P, Verghese GC, Stankovic AM. Phasor dynamics of thyristor-controlled series capacitor systems.
*IEEE Trans. Power Systems*12: 1259-1267, 1997. - Stankovic AM, Verghese GC, Perreault DJ. Randomized modulation of power converters via Markov chains.
*IEEE Trans. Control System Technology*5: 61-73, 1997. - Karl WC, Kulkarni S, Verghese GC, Willsky AS. Local tests for consistency of support hyperplane data.
*J. of Mathematical Imaging and Vision*6: 249-267, 1995. - Milanfar P, Verghese GC, Karl WC, Willsky AS. Reconstructing polygons from moments, with connections to array processing.
*IEEE Trans. Signal Processing*43: 432-443, 1995. - Karl WC Verghese GC, Willsky AS. Reconstructing ellipsoids from projections.
*Computer Vision, Graphics, and Image Processing*56: 124-139, 1994. - Sanders SR, Verghese GC. Lyapunov-based control for switched power converters.
*IEEE Trans. Power Electronics*7: 17-24, 1992. - Sidman SR, DeAngelis FE, Verghese GC. Parametric system identification on logarithmic frequency response data.
*IEEE Trans. Automatic Control*36: 1065-1070, 1991. - Sanders SR, Noworolski JM, Liu XZ, Verghese GC. Generalized averaging method for power conversion circuits.
*IEEE Trans. Automatic Control*6: 251-259, 1991. (Special Issue on Modeling) - Leeb SB, Kirtley JL, Verghese GC. Recognition of dynamic patterns in DC-DC switching converters.
*IEEE Trans. Power Electronics*6(2): 296-302, 1991. - Tsai WK, Parlors AG, Verghese GC. Bounding the states of systems with unknown-but-bounded disturbances.
*Int. J. of Control*52: 881-915, 1990. - Karl WC, Verghese GC. Curvatures of surfaces and their shadows.
*Linear Algebra and Applications*130: 231-915, 1990. - Pérez-Arriaga IJ, Verghese GC, Pagola FL, Sancha JL, Schweppe FC. Developments in Selective Modal Analysis of small-signal stability in electrical power systems.
*Automatica*26: 215-231, 1990. - Vélez-Reyes M, Verghese GC. Developing reduced order electrical machine models using participation factors.
*IMACS Annals on Computing and Applied Math*(Modeling and Simulation) 3: 333-335, 1989. - Massoumnia MA, Verghese GC, Willsky AS. Failure detection and identification in linear time-invariant systems.
*IEEE Trans. Automatic Control*34: 316-321, 1989. - Pagola FL, Pérez-Arriaga IJ, Verghese GC. On sensitivities, residues and participations: Applications to oscillatory stability analysis and control.
*IEEE Trans. Power Systems*4: 278-285, 1989. - Elbuluk ME, Verghese GC, Kassakian JG. Sampled-data modeling and digital control of resonant converters. IEEE Trans.
*Power Electronics*3: 344-354, 1988. - Lou X-C, Willsky AS, Verghese GC. An algebraic approach to time scale analysis of singularly perturbed linear systems.
*Int. J. Control*47: 281-308, 1988. - Lou X-C, Verghese GC, Willsky AS, Coxson PG. Conditions for scale-based decompositions in singularly perturbed systems.
*Linear Algebra and its Applications*98: 387-413, 1988. (Special Issue on Linear Algebra in Electrical Engineering) - Lou X-C, Willsky AS, Verghese GC. Optimally robust redundancy relations for failure detection in uncertain systems.
*Automatica*22: 333-344, 1986. - Verghese GC, Elbuluk ME, Kassakian JG. A general approach to sampled-data modeling for power electronic circuits.
*IEEE Trans. Power Electronics*PE-1: 76-89, 1984. - Levy BC, Castanon DA, Verghese GC, Willsky AS. A scattering framework for decentralized estimation problems.
*Automatica*19(4): 373-384, 1983. - Verghese GC. A ‘Cramer’s Rule’ for the least-norm, least-square-error solution of inconsistent equations.
*Linear Algebra and Its Applications*48: 315-316, 1982. - Verghese GC, Pérez-Arriaga IJ, Schweppe F. Rational approximation via Selective Modal Analysis.
*Circuits, Systems and Signal Processing*1(3-4): 433-445, 1982. (Special Issue on Rational Approximation of Systems) - Verghese GC, Pérez-Arriaga IJ, Schweppe F. Selective Modal Analysis with applications to electric power systems, II: The dynamic stability problem.
*IEEE Trans. Power Apparatus and Systems*PAS-101(9): 3126-3134, 1982. - Pérez-Arriaga IJ, Verghese GC, Schweppe F. Selective Modal Analysis with applications to electric power systems, I: Heuristic introduction.
*IEEE Trans. Power Apparatus and Systems*PAS-101(9): 3117-3125, 1982. - Willsky AS, Bello M, Castano DA, Levy BC, Verghese GC. Combining and updating of local estimates and regional maps along sets of one-dimensional tracks.
*IEEE Trans. Auto. Control*AC-27(4): 799-812, 1982. - Verghese GC, Levy BC, Kailath T. A generalized state-space for singular systems.
*IEEE Trans. Automatic Control*AC-26(4): 811-831, 1981. - Verghese GC, Kailath T. Rational matrix structure.
*IEEE Trans. Automatic Control*AC-26: 434-438, 1981. - Verghese GC, Friedlander B, Kailath T. Scattering theory and linear least-squares estimation, III: The estimates.
*IEEE Trans. Automatic Control*AC-25(4): 794-802, 1980. - Verghese GC, Van Dooren P, Kailath T. Properties of the system matrix of a generalized state-space system.
*Int. J. Control*30(2): 235-243, 1979.

## Selected Conference Publications

- Ranger M, Johnston CC, Rennick JE, Limperopoulos C, Heldt T, du Plessis AJ. Near-infrared spectroscopy (NIRS) to measure nociception following noxious stimulation in critically ill infants. 14th World Congress on Pain, Milan, Italy, 2012.
- Fanelli A, Signorini MG, Heldt T. Extraction of Fetal Heart Rate from Maternal Surface ECG with Provisions for Multiple Pregnancies. Proceedings of the 34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 6165-6168, 2012.
- Irena Hwang, Faisal Kashif, Marek Czosnyka, Thomas Heldt, George Verghese. A Frequency-Domain Approach to Model-Based Noninvasive Intracranial Pressure Estimation from Arterial Pressure and Cerebral Blood Flow Velocity. 34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, San Diego, USA, 2012.
- Haslam B, Gordhandas A, Ricciardi C, Verghese GC, Heldt T. Distilling Clinically Interpretable Information from Data Collected on Next-Generation Wearable Monitors. Proceedings of the 33rd Annual Conference of the IEEE Engineering in Medicine and Biology Society, 1729-1732, 2012.
- Haslam B, Gordhandas A, Ricciardi C, Heldt T, Verghese GC. Relating Noninvasive Cardiac Output and Total Peripheral Resistance Estimates to Physical Activity in an Ambulatory Setting. Proceedings of the AAAI Spring Symposium on Computational Physiology, 27-31, 2011.
- Gordhandas A, Heldt T, Verghese GC. Real-time extraction and analysis of key morphological features in the electrocardiogram for data compression and clinical decision. Proceedings of the AAAI Spring Symposium on Computational Physiology, 15-18, 2011.
- Heldt T, Verghese GC. Model-based data integration for clinical environments. Proceedings of the 32nd Annual Conference of IEEE Engineering in Medicine and Biology Society, 5209-5212, 2010.
- He DD, Winokur ES, Heldt T, Sodini CG. The ear as a location for wearable vital signs monitoring. Proceedings of the 32nd Annual Conference of IEEE Engineering in Medicine and Biology Society, 6389-6392, 2010.
- Kashif FM, Heldt T, Verghese GC. Model-based estimation of intracranial pressure and cerebral autoregulation. Computers in Cardiology 35:369-372, 2008.
- Parlikar TA, Heldt T, Ranade GV, Verghese GC. Model-based estimation of cardiac output and total peripheral resistance. Computers in Cardiology 34:379-381, 2007.
- Heldt T, Chang JL, Verghese GC, Mark RG. Cycle-averaged models of cardiovascular dynamics. Proc. of the 5th IFAC Symposium on Modelling and Control in Biomedical and Biological Systems 387 – 392, 2003.

## Patents

- Parlikar TA, Ranade GV, Heldt T, and Verghese GC. Model-Based Method for Continuous Determination of Cardiac Output and Peripheral Vascular Resistance. U.S. Patent 8,282,564, 10/09/2012.
- Parlikar TA, Heldt T, Mukkamala R, and Verghese GC. Model-Based Method for Continuous Determination of Cardiac Ejection Fraction and Ventricular End-diastolic Volume. U.S. Patent 8,235,910, 08/07/2012
*.* - Parlikar TA, Heldt T, Mark RG, and Verghese GC. System and Method for Prediction and Detection of Circulatory Shock. U.S. Patent 8,262,579, 09/11/2012.
- Kashif FM, Heldt T, Verghese GC. Systems, Devices, and Methods for Noninvasive or Minimally-Invasive Estimation of Intracranial Pressure and Cerebrovascular Autoregulation, U.S. Patent Application 2010/0063405A1 allowed for issuance as a patent, 10/02/2012.

## Recent Presentations

2012Heldt T. Challenges (and some solutions) in patient monitoring. Samsung Advanced Institute of Technology, Yongin, South Korea, December 2012.

Heldt T, Verghese GC. Model-based noninvasive intracranial pressure estimation. National Taiwan University Medical Electronics Workshop, National Taiwan University Hospital, Taipei, Taiwan, November 2012.

Heldt T, Hwang I, Kashif FM, Czosnyka M, Verghese GC. Time- and frequency-domain approaches to model-based estimation of intracranial pressure. Mini-symposium on Information derived from arterial pressure waveform and its clinical significance, IEEE Engineering in Medicine and biology Conference, San Diego, CA, USA, September 2012.

Heldt T. “Model-Based Neuromonitoring,” University of Maryland Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, USA, September 2012.

Heldt T, Kashif FM, Verghese, GC. Model-based estimation of intracranial pressure. Grand Rounds, Combat Casualty Care Directorate, U.S. Army Medical Research and Material Command and Telemedicine & Advanced Technology Research Center, Fort Detrick, Maryland, July 2012.

2011Heldt T, Kashif FM, Verghese GC. Model-based estimation in biomedicine – towards noninvasive brain monitoring. Kangwon National University and Korean Advanced Institute of Science and Technology, Korea, November 2011.

Haslam B, Gordhandas A, Ricciardi C, Verghese GC, Heldt T. Distilling clinically interpretable information from data collected on next-generation wearable sensors. IEEE Engineering in Medicine and Biology Conference, Boston, MA, September 2011.

Heldt T, Kashif FM, Verghese GC. Noninvasive monitoring of intracranial pressure. MIT Medical Electronics Device Realization Center, Workshop on Next-Generation Medical Electronic Systems, Cambridge, MA, 2011.

Haslam B, Gordhandas A, Ricciardi C, Heldt T, Verghese GC. Relating noninvasive cardiac output and total peripheral resistance estimates to physical activity in an ambulatory setting. AAAI Spring Symposium 2011 on Computational Physiology, Stanford, CA, 2011.

Gordhandas A, Heldt T, Verghese GC. Real-time extraction and analysis of key morphological features in the electrocardiogram for data compression and clinical decision. AAAI Spring Symposium 2011 on Computational Physiology, Stanford, CA, 2011.

2010Kashif FM, Heldt T, Novak V, Czosnyka M, Verghese GC. Noninvasive continuous estimation of intracranial pressure: a model-based, patient-specific, and calibration-free approach. 14th International Conference on Intracranial Pressure and Brain Monitoring, Tübingen, Germany, 2010.

Heldt T, Kashif FM, O’Leary HM, Suleymanci M, du Plessis AJ, Verghese GC. Comprehensive continuous cerebral oxygen metabolism monitoring through ventilator-gated analysis of cerebral near-infrared spectroscopy. 14th International Conference on Intracranial Pressure and Brain Monitoring, Tübingen, Germany, 2010.

Heldt T, Verghese GC. Integrating data, models, and reasoning in critical care. Advanced Technology Applications for Combat Casualty Care (ATACCC) Conference, St. Pete’s Beach, FL, August 2010.

Heldt T. Cardiac output estimation: an engineering perspective. Annual meeting of the Pediatric Academic Societies, Vancouver, CA. May 2010.

Heldt T, Verghese GC. Multiparameter data archiving and exploration – implications for outcome analysis. Grand Rounds, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, April 2010.

Ranger M, Heldt T, O’Leary H, Suleymanci M, Johnston C, du Plessis AJ. Description of global cerebrovascular activation during noxious stimulus in critically ill premature infants. 8th International Symposium on Pediatric Pain, Acapulco, Mexico, March 2010.

Kashif F, Heldt T, Novak V, Czosnyka M, Verghese GC. Noninvasive cerebrovascular monitoring, Annual Stroke Conference, San Antonio, TX, February 2010.

2009Kashif F, Heldt T, Novak V, Czosnyka M, Verghese GC. Noninvasive model-based cerebrovascular monitoring for neurotrauma. CIMIT Innovation Congress, Boston, MA, October 2009.

Verghese GC. Deconstructing integrative models: the case for model reduction. Workshop on Computational Challenges in Integrative Biological Modeling, Mathematical Biosciences Institute, Ohio State University, Columbus, OH, October 2009.

Heldt T, Model-based estimation in biomedicine. Workshop on Computational Challenges in Integrative Biological Modeling, Mathematical Biosciences Institute, Ohio State University, Columbus, OH, October 2009.

Verghese GC. Getting to the gray box: Some challenges for model reduction. Inaugural plenary lecture, American Control Conference, St. Louis, MO, June 2009. (Video available here.)

Heldt T. Caring for the micro-patient: device needs in the neonatal intensive care unit. Microsystems Technology Laboratory, MIT, Cambridge, MA, March 2009.

Heldt T, Verghese GC. Cardiac output estimation: a signal processing perspective. Workshop on Safe and Effective Devices for Use in the Neonatal Intensive Care Unit, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, February 2009.

2008Heldt T. Model-based estimation in biomedicine. Department of Biotechnology, Indian Institute of Technology Madras, India, August 2008.

Heldt T, Verghese GC. Subset selection for reduced-order parameter estimation, SIAM Life Science Conference, Montreal, CA, August 2008.